The overall objectives of the proposed research are: (1) to study the growth regulation of normal and tumor intestinal epithelial cells in vitro; and (2) to determine the susceptibility to chemical carcinogenesis of normal epithelial cell lines derived from different portions of the rat intestine; and (3) to attempt to establish normal epithelial cell lines from human intestine. The studies comparing the growth regulation of normal intestinal cells, and of tumor cell lines derived from dimethylhydrazine-induced tumors of the small and large intestine will focus, in particular, on the effect of various hormones, and of growth inhibitory factors which we have found present in villus cell extracts, in the culture medium of hydrocortisone-treated normal cell cultures, and in adult rat serum. We will make attempts to at least partially purify these inhibitory substances, to characterize their activity in vitro, and their possible role in the growth regulation of intestinal epithelial cells in vivo. In the course of these studies we will determine growth rates, DNA synthesis, duration of cell cycle phases, kinetics of growth inhibition and/or stimulation in the presence or absence of the various hormones and other factors. Susceptibility to chemical carcinogenesis will be studied in intestinal epithelial cell lines derived from different portions of rat small and large intestine; the progress of malignant transformation will be monitored by following various possible cellular changes including: an abnormal cell morphology, changes in saturation density, growth in soft agar, plasminogen activator production and decreased fibronectin deposition. Tumorigenicity in vivo of chemically transformed cells will be tested by inoculating them into rats. In our attempts to establish normal epithelial cell cultures from human intestine we will follow, at least initially, a protocol identical to that used for the establishment of epithelial cell lines from rat small intestine. If obtained, the human cell lines will be characterized by morphologic and immunologic criteria similar to our studies of rat intestinal cells.